In a sidelight-type backlight module, a cold cathode fluorescent lamp (CCFL) or a light emitting diode (LED) is currently adopted for serving as a light source. To satisfy the requirement of developing thinning devices, a large scale backlight module has been gradually designed to be incident by light rays at a single end. The single-end incident type becomes a design tendency as the emitting efficiency of the light source is improved. However, there are problems accompanied as well. FIG. 1 is a schematic diagram showing a structure of a conventional light guide plate. The light guide plate 100 shown in FIG. 1 comprises a light incidence surface 101, a reflection surface 102, a light emitting surface 102, and a lateral reflection surface 104. The light source 110 in FIG. 1 is an ultraviolet light source. After the light rays emitted from the light source 110 enters the light guide plate 100 via the light incidence surface 101, the light rays are converted to white rays by a transforming fluorescent powder 111, wherein the transforming fluorescent powder 111 is a mixture of a yellow-ray fluorescent powder and a blue-ray fluorescent powder. The total internal reflection formed by the converted white rays is then destroyed by optical microstructures 105 on the reflection surface 102 and the rays are emitted from the light emitting surface 103. However, when the light rays are propagated in the light guide plate, the light rays encountering the optical microstructures 105 will be scattered for each collision and at the same time a part of energy of the light rays will be absorbed. Therefore, the spectrum of the light rays will be changed for each time the light rays are scattered. When the light rays are propagated from an end of the light guide plate 100 to the other end, the color of the light rays is gradually altered. In the conventional sidelight-type backlight module, the optical microstructures 105 of the light guide plate 100 can be formed into a printed type and a non-printed type. An ink on the printed-type optical microstructures 105 mainly absorbs short-wavelength light rays emitted from the light source 110, and therefore a color degree of the light rays will become large (that is, the color will deviate to a yellow color) when the light rays are propagated to an end away from the light incidence surface 101. A panel color difference will be occurred eventually. That is, the color of respective points is non-uniform at a backlight side. The bigger is the size of the light guide plate, more apparent is the color difference. This may seriously affect visual quality level and the quality of products. The non-printed-type light guide plate is a light guide plate adopting microstructures made of methylmethacrylate styrene (MS) or other materials. The MS material or the other material itself will absorb short-wavelength light rays and will cause the panel color difference as well.
Therefore, it is necessary to provide a light guide plate and a backlight module utilizing an ultraviolet light source for solving the problems in the conventional skills.